HomeMy WebLinkAbout005 WATER DEMAND MEMODomestic Water Demand Memo 04/11/2025
Allied Engineering Services, Inc. Memo Page 2
A maximum day to average day ratio of 2.3:1 and Peak Hour to average day ratio of 3:1 were used as
outlined in section V.A.4 of the COB Design Standards and Specifications. Irrigation estimates for the
existing and proposed landscaping were provided by the landscape architect at 24.3 gallons/day. Please
see the attached calculations for additional information. A summary is provided below.
2020 COB Design Standards - Residential Dwelling Units:
Number of Dwellings = 13
Assumed Occupancy Rate = 2.11 people/unit
Water Use Flow Rate per Capita = 170 gallons/capita/day
Average Day Demand = 4,663 gallons/day
2024 COB Design Standards - Residential Dwelling Units:
Number of Dwellings = 13
Assumed Occupancy Rate = 2.17 people/unit
Water Use Flow Rate per Capita = 135 gallons/capita/day
Average Day Demand = 3,808 gallons/day
1,375-ft2 Office:
Number of Employees = 10
Average Water Use Flow Rate per Employee = 13 gallons/employee/day
Average Day Demand = 130 gallons/day
549-ft2 Bakery:
Number of Employees = 4
Average Water Use Flow Rate per Employee = 10 gallons/employee/day
Number of Customers = 100 (rough assumption)
Average Water Use Flow Rate per Customer = 6 gallons/customer/day
Average Day Demand = 640 gallons/day
Total Water Demand:
Irrigation Demand = 24.3 gallons/day
Maximum Day Factor = 2.3:1
Peak Hour Factor = 3.0:1
Total with 2020 COB Design Standards
Total Average Day Demand = 5,457 gallons/day
Maximum Day Demand = 12,552 gpd (8.72 gpm)
Peak hour demand = 16,372 gpd (11.37 gpm)
Total with 2024 COB Design Standards
Total Average Day Demand = 4,602 gallons/day
Maximum Day Demand = 10,586 gpd (7.35 gpm)
Peak hour demand = 13,808 gpd (9.59 gpm)
Please contact Wyatt Alt, Cole Oshiro-Leavitt and/or Rory Romey at 406-582-0221 or
walt@alliedengineering.com; coshiro-leavitt@alliedengineering.com; rromey@alliedengineering.com
with any questions or if additional information is required.
Domestic Water Demand Memo 04/11/2025
Allied Engineering Services, Inc. Memo Page 3
2020 COB Standards Residential Dwelling Units:
Number of Dwellings: 13 Units
Assumed Occupancy Rate: 2.11 People/Unit
Water Use Flow Rate per Capita: 170 Gallons/Capita/Day
Average Day Demand: 4663.1 Gallons/Day
2024 COB Standards Residential Dwelling Units:
Number of Dwellings: 13 Units
Assumed Occupancy Rate: 2.17 People/Unit
Water Use Flow Rate per Capita: 135 Gallons/Capita/Day
Average Day Demand: 3808.35 Gallons/Day
1,375-ft2 Office: Number of Employees: 10 Employees
Average Water Flow Rate per Employee: 13 Gallons/Employee/Day
Average Day Demand: 130 Gallons/Day
549-ft2 Bakery: Number of Employees: 4 Employees
Average Water Flow Rate per Employee: 10 Gallons/Employee/Day
Number of Customers: 100 Customers
Average Water Flow Rate per Customer: 6 Gallons/Customer/Day
Average Day Demand Employees: 40 Gallons/Day
Average Day Demand Customers: 600 Gallons/Day
Average Day Demand Bakery: 640 Gallons/Day
Total Water Demand: Irrigation Demand: 24.3 Gallons/Day
Maximum Day Factor: 2.3 Peak Hour Factor: 3.0
2020 COB Standards Total Average Day Demand: 5457.4 Gallons/Day
Maximum Day Demand: 12552.0 Gallons/Day
Maximum Day Demand: 8.72 Gallons/Minute
Peak Hour Demand: 16372.2 Gallons/Day
Peak Hour Demand: 11.37 Gallons/Minute
2024 COB Standards: Total Average Day Demand: 4602.65 Gallons/Day
Maximum Day Demand: 10586.1 Gallons/Day
Maximum Day Demand: 7.35 Gallons/Minute
Peak Hour Demand: 13808.0 Gallons/Day
Peak Hour Demand: 9.59 Gallons/Minute